Right - when you are using DataTables, then Editor can automatically listen for the xhr event and check to see if there are any options for its list fields. Since you aren't using DataTables there is no Ajax request that Editor can automatically listen to, so there is no way for it to populate the options.

Two options:

Make the Ajax request to get the options yourself - then use editor.field('customer.treatment_id').update( ...options... );, or